In traditional method for preparing nano composite materials, nano particles are mixed into organics physically, or grafted onto organics after being modified and organized on surface, which may lead to the problem of reunion and sedimentation. In recent years, researchers in the world have contributed to improve the dispersion of nano particles, and as a result, a situ polymerization method, which is an advanced and effective preparation method for nano composite materials, has been popular in the public. However, this method is only used to modify the traditional nano composite organic resin (eg. polyester resin, epoxy resin, acrylic resin), but rarely applied on the preparation for the nano silicone resin.
In the synthetic method for vinyl organic/inorganic nano-hybrid material published at Nov. 17, 1999 and numbered CN1235170A, a traditional Sol-Gel method is applied. A Sol-Gel precursor tetraethoxysilane is hydrolyzed to a sol with catalysis of a hydrochloric acid, and a gel is obtained after adding a vinyl monomer into the sol at 30-50° C. Then a situ polymerization takes place at 5-45° C. under y ray radiation of 5-100 KGy for 4-20 h. In the end, the hybrid material is obtained after heating and drying the sample at 60-80° C. under y ray radiation for 1-2 weeks.
In traditional insulating varnish made of silicone resin, a solvent based silicone resin is used. It's unavoidable to produce pollution to the environment because of the volatile gas in production. and the energy consumption is extremely high since the high-temperature curing is necessary. However, most of the few solvent-free silicone resins have high viscosity and low activity and need to be cured at a high temperature. The mass percent of the reactive diluent added should be more than 30% since the viscosity of the resin is too high, resulting in the volatile matter content exceeding 5%. As a result, the heat resistance and mechanical performances are degraded. In a VPI application, the resin should be heated in use and preserved at a low temperature after use, which not only needs a high-quality device but also is tedious in process. As the fast development of the motor market in the world, the motor manufacture is developed towards high efficiency, energy conservation and miniaturization. The heat-resistant level and energy conservation level of the insulating paint are demanded to be higher as well as the corona-resistant ability, in order to satisfy the demand of the industry. In the prior art, directly mixing with nano particles is always used to enhance the corona-resistant ability, however, the effective is poor because the particles are easy to unite and settle. In general, the silicone based insulating varnish in the prior art don't satisfy the demand of energy conservation, emission reduction, environmentally, and economically.